In animal agriculture, increasing milk production and improving milk quality of the milk produced have been primary goals when feeding lactating dairy animals, such as dairy cows. Depending on the animal, the feed components may vary considerably. For example, ruminants are able to digest fibrous plant based foods, or roughage, that are indigestible to non-ruminants. Ruminants may include lactating animals such as, for example, cattle, goats, sheep, and dairy cows. Illustrative types of roughages include hay, grass silage, corn silage, straw and pasture, as well as various whole grain/leguminous silages and other fodders.
For efficient milk production, ruminants may also be given, in addition to roughage, a feed concentrate that may include energy components (that is, carbohydrates and fats), protein components, minerals, micronutrients, and vitamins. Some examples of common feed items include grain feeds (such as corn, oats, barley, and wheat), vegetable oilseed crushes or meal (rapeseed), and soybeans. A large variety of byproducts from food industries may also be used.
By means of microbes within the rumen digestive system, most of the energy and nutrients needed by the ruminant are obtained from the feed. Nitrogen containing materials, which may be natural proteins or non-protein sources such as urea, may be broken down and converted into amino acids and proteins by the microorganisms of the rumen. Both urea and natural protein are broken down by the microorganisms in the rumen to ammonia and carbon fragments, and are thereafter reconstituted, together with carbohydrate degradation products, to form amino acids. The amino acids may be used to build protein that may subsequently be used by the host animal. The carbohydrate degradation process provides energy for the amino acid reconstitution process.
However, urea may not be efficiently used by the host animal. In the rumen, via urease, urea may be converted into ammonia at a very rapid rate, generally, at a rate in excess of the rate at which the urea can be converted into useful products by the microorganisms. Any leftover ammonia may be converted back into urea to be expelled with urine, or may accumulate to toxic levels in the animal. Urea expelled in the urine may be converted to ammonia on the ground by contact with urease often found in the feces or soil. In the air, ammonia can combine with other compounds to form ammonium nitrate and ammonium sulfate, which are fine particulates. These particulates are of concern for human health and are regulated under the Clean Air Act. Therefore, regulating the production of ammonia from urea to provide an optimal concentration of ammonia in the digestive system and minimizing the release of ammonia from animal feeding operations is desirable.